1. Field of the Invention
The present invention relates generally to a ball valve, and more particular to a ball valve with a leakage-proof between the ball and the valve seat. The ball valve of the present invention is easy to assemble also.
2. Description of the Related Art
FIG. 7 shows a conventional multi-way ball valve, which includes a valve seat 100, a ball 200, a shaft 300 and four lids 400. The valve seat 100 has a chamber 101 therein and four bores communicated with the chamber 101. The ball 200, which is received in the chamber 101 of the valve seat 100, has two channels 201. The shaft 300 is inserted into the bore of the valve seat 100 and connected to the ball 200. The shaft 300 is turned to rotate the ball 200 to change the orientations of the channels 201. The lids 400 are fixed to the valve seat 100 to close the bores respectively, each of which has a pad 401 at an interior side thereof for leakage-proof.
The pads 401 of the lids 400 are pressed on valve seat 100 rather than the ball 200, such that there is a residual space 102 in the valve seat 100. Fluid flowing through the ball valve will flow into the residual space 102 when the ball 200 is turned. If the fluid is a putrescible fluid, the fluid received in the residual space 102 will be putrefied after a long time of use, and the putrefactive fluid may be mixed with the flesh fluid and flow out that will cause pollution of the fluid.
An improved ball valve provides the lids with a concave portion at the interior side to fit the ball. This kind of lid is provided with two inclined face at opposite sides of the concave portion that make the ball valve is hard to assemble. Furthermore, it breaks the leakage-proof also.